Skip to content

Intraspecific Combat in Zuul and the Evolution of Tail Clubs in Armored Dinosaurs

December 7, 2022

Today we revealed Zuul put back together for the first time, and what its completely preserved armor and skin tell us about the behavior of armoured dinosaurs, and the evolution of tail clubs in ankylosaurs. This was another fun collaboration with lab alum Dr. Victoria Arbour, as well as Dr. Lindsay Zanno. Another lab alum, Henry Sharpe, provided the dynamic supporting artwork of two Zuul in combat for the media release.

Here is the Press Release:

Scientists from the Royal Ontario Museum (ROM), Royal BC Museum, and North Carolina Museum of Natural Sciences have found new evidence for how armored dinosaurs used their iconic tail clubs.

The exceptional fossil of the ankylosaur Zuul crurivastator has spikes along its flanks that were broken and re-healed while the dinosaur was alive—injuries that the scientists think were caused from a strike by another Zuul’s massive tail club. This suggests ankylosaurs had complex behavior, possibly battling for social and territorial dominance or even engaging in a “rutting” season for mates. The research is published in the journal Biology Letters.

The digitally reassembled skeleton of Zuul crurivastator.

The 76-million-year-old, plant-eating dinosaur, part of the Royal Ontario Museum’s vertebrate fossil collection, is named after the fictional monster “Zuul” from the 1984 movie “Ghostbusters.” Initially the skull and tail had been freed from the surrounding rock, but the body was still encased in 35,000 pounds of sandstone. After years of work, the body was revealed to have preserved most of the skin and bony armor across the entire back and flanks, giving a remarkable view of what the dinosaur looked like in life.

Zuul’s body was covered in bony plates of different shapes and sizes, and the ones along its sides were particularly large and spiky. Interestingly, the scientists noticed that a number of spikes near the hips on both sides of the body were missing their tips, and the bone and horny sheath had healed into a blunter shape. The pattern of these injuries was more consistent with being the result of some form of ritualized combat, or jousting with their tail clubs, and probably wasn’t caused by an attacking predator like a tyrannosaur because of where they were located on the body.

“I’ve been interested in how ankylosaurs used their tail clubs for years and this is a really exciting new piece of the puzzle,” says lead author Dr. Victoria Arbour, Curator of Paleontology at the Royal BC Museum and former NSERC postdoctoral fellow at the Royal Ontario Museum.

“We know that ankylosaurs could use their tail clubs to deliver very strong blows to an opponent, but most people thought they were using their tail clubs to fight predators. Instead, ankylosaurs like Zuul may have been fighting each other.”

Zuul’s tail was about three meters (10 feet) long, with sharp spikes running along its sides. The back half of the tail was stiff and the tip was encased in huge bony blobs, creating a formidable sledgehammer-like weapon.

Zuul crurivastator means “Zuul, the destroyer of shins,” a nod to the idea that tail clubs were used to smash the legs of bipedal tyrannosaurs. The new research doesn’t refute the idea that tail clubs could be used in self-defense against predators, but shows that tail clubs would also have functioned for intra-species combat—a factor that more likely drove their evolution. Today, specialized animal weapons like the antlers of deer or the horns of antelopes have evolved to be used mostly for fighting members of the same species during battles for mates or territory.

Two Zuul in bitter combat. Amazing art by Henry Sharpe.

Years ago, Arbour had put forward the idea that ankylosaurs might have clubbed each other in the flanks, and that broken and healed ribs might provide evidence to support this idea. But ankylosaur skeletons are extremely rare, making it hard to test this hypothesis. The completely preserved back and tail of Zuul, including skin, allowed for an unusual glimpse into the lives of these incredible armored dinosaurs

“The fact that the skin and armor are preserved in place is like a snapshot of how Zuul looked when it was alive. And the injuries Zuul sustained during its lifetime tell us about how it may have behaved and interacted with other animals in its ancient environment,” said Dr. David Evans, Temerty Chair and Curator of Vertebrate Paleontology at the Royal Ontario Museum.

The remarkable skeleton of Zuul was found in the Judith River Formation of northern Montana, and was acquired by the Royal Ontario Museum through the generous support of the Louise Hawley Stone Trust.

Here is a link to the paper:

Arbour, V., Zanno, L, and Evans, D. C.  2022.  Palaeopathological evidence for intraspecific combat in ankylosaurid dinosaurs. Biology Letters 18(12). Link here:

The research has already generated some media interest:

The Ankylosaur’s Tail-Club Wasn’t Only Swinging at T. rex: New York Times

Ankylosaurs used their sledgehammer tails to fight each other: CNN

Armored dinos may have used their tail clubs to bludgeon each other: Science News

Rare fossil reveals ‘destroyer of shins’ dinosaurs fought each other: New Scientist


Family life of sibling sabre-toothed cats

February 17, 2021

On January 7, we published a new and intriguing study in iScience¸ which documents a family group of the sabre-toothed cats whose remains were discovered in present-day Ecuador. By studying the fossils, collected for the ROM in the early 1960s, we were able to show that while the supersized Ice Age cats grew quite quickly, they also appeared to stay with their mother for longer than some other large cats before forging their own path.

Sabre-toothed cubs playing together based on the Coralito fossil assemblage. Credit: Illustration by Danielle Dufault © Royal Ontario Museum

“This study started out as a simple description of previously unpublished fossils,” says Ashley Reynolds, a graduate student based at the Royal Ontario Museum who led the study while completing her PhD research in Ecology & Evolutionary Biology at the University of Toronto. “But when we noticed the two lower jaws we were working on shared a type of tooth only found in about five percent of the Smilodon fatalis population, we knew the work was about to become much more interesting.”

Encouraged by this new discovery, the researchers dug deeper and found that they were likely looking at three related individuals: one adult and two “teenaged” cats. What’s more, they were able to determine that the younger cats were at least two years old at the time of their death, an age at which some living big cats, such as tigers, are already independent.

To support this conclusion, the team studied the preservation and formation of the Ecuadorian site (an area of study called taphonomy), based on historic collecting records and the suite of clues on the fossil bones themselves.

Historically, Smilodon specimens that have largely been collected from “predator trap” deposits, such as the famous La Brea Tar Pits in Los Angeles, California. But the Ecuador deposit, which formed on an ancient coastal plain, is likely derived from a catastrophic mass death event. This means that, unlike the “traps,” all the fossils in the deposit died at the same time. As this preserves a snapshot of an ecosystem, fossils like these can provide new and unique insights into the behaviour of extinct species.

“The social lives of these iconic predators have been mysterious, in part because their concentration in tar seeps leaves so much room for interpretation” says Dr. Kevin Seymour, Assistant Curator of Vertebrate Paleontology at the ROM and a co-author of this study, “This historic assemblage of sabre-cat fossils from Ecuador was formed in a different way, allowing us to determine the two juveniles likely lived, and died, together—and were therefore probably siblings”

The fossils were collected from Coralito, Ecuador in 1961 by A. Gordon Edmund, who was curator of Vertebrate Palaeontology at the ROM from 1954-1990, and Roy R. Lemon, who was curator of Invertebrate Palaeontology from 1957-1969. Together, Edmund and Lemon collected tonnes of tar-soaked sediment which was later prepared at the ROM.

“These world-famous collections made 60 years ago have been studied for years, but a measure of their importance is that they continue to produce new insights into the lives of these extinct animals” says Dr. David Evans, Temerty Chair of Vertebrate Palaeontology at the Royal Ontario Museum and Reynolds’s thesis supervisor.

Article Reference: Reynolds, A.R., Seymour, K.L., and Evans, D.C. 2021. Smilodon fatalis siblings reveal life history in a saber-toothed cat. iScience 24(1): 101916. doi: 10.1016/j.isci.2020.101916 .

Sabre-toothed Smilodon Comes to Canada!

October 4, 2019

Today we officially welcome the iconic ‘sabre-toothed tiger’ Smilodon fatalis to Canada. New research led by lab Ph.D. candidate Ashley Reynolds shows that the fearsome sabre-toothed predator, Smilodon fatalis, lived in Alberta, Canada, during the Ice Age- between 35,000 and 50,000 years ago. This identification marks the northern-most record of the sabre-toothed cat, and extends its range by a whopping 1,000 kilometres.

Illustration of Smilodon fatalis by palaeoartist Henry Sharpe. © Henry Sutherland Sharpe.

Life reconstruction of Smilodon fatalis in the Medicine Hat area approximately 40,000 years ago. Original artwork courtesy of Henry Sharpe

Our new study documents the first known occurrence of a Smilodon fossil in Canada, based on a stout partial hand bone of one of the cat’s large forepaws, that are part of teh Royal Ontario Museum’s collections. Previously, the most northerly recorded find of Smilodon fossils was in American Falls Reservoir, Idaho. Smilodon, best known from Tar Pit deposits in California and South America, is one of the most famous fossil animals and a key top predator in its ecosystems, so it’s  exciting to find evidence of this iconic sabre-toothed cat in Canada. Smilodon, would have hunted large herbivores that were also present at the time, including camels, horses, giant ground sloths, and even young mammoths and mastodons.

The study also documents bone specimens from three other types of cat, including the American lion (Panthera atrox), a lynx or bobcat (Lynx sp.), and what may be the most southerly record of the cave lion (Panthera cf. Panthera spelaea), which was previously only known in North America from fossils found in Alaska and the Yukon.

The fossils held at the ROM were collected in the late 1960s by University of Toronto palaeontologist C. S. Churcher and colleagues in the area around Medicine Hat, Alberta. With this research paper, the researchers have now confirmed the species to which the bones belonged to. This past summer, Ashley Reynolds and I followed up by leading a team of graduate students to explore the Ice Age deposits and revisit the fossil sites in Medicine Hat to see if we can find more evidence of these ancient big cats.

The paper describing the Smilodon bone and remains of other fossils cats from Medicine Hat, Alberta was published online October 4, 2019, in the Canadian Journal of Earth Sciences.

Article Reference:  Reynolds, A.R., Seymour, K.L., and Evans, D.C. 2019. Late Pleistocene records of felids from Medicine Hat, Alberta, including the first Canadian record of the sabre-toothed cat Smilodon fatalis. Canadian Journal of Earth Sciences 56: 1052-1060. doi: 10.1139/cjes-2018-0272

Read the press release here.

Popular Press:

Sabre-toothed cat fossil places the predator in southern Alberta

Canada’s first sabre-toothed cat fossil found in Medicine Hat

Scientists find ‘exciting’ fossil evidence of sabre-toothed cat in southern Alberta

Public lecture:  ROM Daytime lecture: “The North Remembers: Ice Age Fossil Finds from Medicine Hat, Alberta.”  Royal Ontario Museum. Thursday, November 14, 2019, 11:00 am

We Have a Logo!

November 4, 2018

Lab palaeo-artist extraordinare Danielle Dufault has recently made us an amazing logo. It’s basically a coat-of-arms for the ROM/University of Toronto vertebrate palaeontology research group, with our ambassador Parasaurolophus walkeri taking pride of place in the center, flanked by the sabre-cat Smilodon, the ankylosaur Zuul crurivastator, and Acheroraptor temertyorum in the foreground. Thanks Danielle for the awesome artwork- it looks great on our new T-shirts and caps!


Currie’s Alberta Hunter

July 17, 2017

Today, my research group published a paper identifying and naming a new species of troodontid dinosaur in honour of Dr. Philip J. Currie.  Albertavenator curriei, meaning “Currie’s Alberta hunter”, stalked Alberta, Canada, about 71 million years ago in what is now the Red Deer River Valley. The find recognizes Currie for his decades of work on predatory dinosaurs of Alberta. The paper was co-authored by University of Toronto PhD students and lab members Thomas Cullen and Derek Larson, as well as one of my undergrad students Adam Rego. Our research on the new species was published on July 17 in the Canadian Journal of Earth Sciences.

Albertavenator_Courtesy Oliver_Demuth

Life reconstruction of Albertavenator curriei by Oliver Demuth.

The bones of Albertavenator were found in the Horseshoe Canyon Formation, in the badlands surrounding the Royal Tyrrell Museum, which Dr. Currie played a key role in establishing in the early 1980s. The rocks around the museum are the same age as some of the most fossiliferous rocks in the area of the newly erected Philip J. Currie Museum, also named in Currie’s honour. Phil has already has several dinosaurs named after him, and this is the second one from Alberta, where he has made his biggest impact. Its widely known in the palaeontological community that Phil’s favorite type of dinosaur is Troodon (hence the logo for the new P. J. Currie Museum). Albertaventator becomes the third troodontid named after him- Liaoningvenator curriei came out while our paper was in press.

We based Albertavenator on two partial skull bones, and feel its likely that a dentary from the same formation belongs to the same species. This doesn’t sound like much- and its not- but its the only troodontid skull material from the Horseshoe Canyon, and some of the most diagnostic troodontid material from the entire Maastrichtian of North America. Other than teeth, troodontid fossils are very, very rare in twilight of the Cretaceous in North America.  In preliminary assessments, palaeontologists believed that the fragmentary bones of Albertavenator belonged to its close relative Troodon, which lived around 76-million-years-ago — five million years before Albertavenator. Both dinosaurs walked on two legs, were covered in feathers, and were about the size of a person. New comparisons of bones forming the top of the head reveal that Albertavenator had a distinctively shorter and more robust skull than Troodon, its famously brainy relative.

Albertavenator_hand_Courtesy Kentaro Chiba

The holotype frontal bone of Albertavenator curriei, showing the brain cavity.

Identifying new species from fragmentary fossils is a challenge. The delicate bones of these small feathered dinosaurs are very rare. We were lucky to have a critical piece of the skull- frontal bones (the bones that form our forehead), that allowed us to distinguish Albertavenator as a new species. The identification of a new species of troodontid in the Late Cretaceous of North America indicates that small dinosaur diversity during this well studied time period is likely underestimated due to the difficulty of identifying species from fragmentary fossils.  It was only through our detailed anatomical and statistical comparisons of the skull bones that we were able to distinguish between Albertavenator and Troodon. The work confirms previous predictions by Lindsay Zanno and Tony Fiorillo that the diversity of troodontids in the Late Cretaceous of North America in particular is underestimated due to over-synonymization of fragmentary, generally non-diagnostic material.

Complicating matters of this new find are the hundreds of isolated teeth that have been found in Alberta and previously attributed to Troodon. Teeth from a jaw that likely pertains to Albertavenator appears very similar to the teeth of Troodon, making them unusable for distinguishing between the two species. Our morphometric study of troodontid teeth from the latest Cretaceous of North America strongly suggests that the holotype tooth (yes, a single tooth) of Troodon formosus is not valid to the species level- but more work will need to be done to confirm this, so we didn’t formally sink everyone’s favorite brainy dinosaur. Ultimately, more complete specimens from the Judith River Formation are needed to resolve this issue.

DSC_1077_Courtesy Kentaro Chiba

Comparison of frontals of ‘Troodon’ inequalis (left) and Albertavenator curriei (right).

The fossils of Albertavenator were found in the early 1990s and studied  in the collections of the Royal Tyrrell Museum. This is another example of a new species of dinosaur being discovered by re-examining museum research collections, which continually add to our understanding of evolution of life on Earth. This study suggests that more detailed studies of fragmentary fossils may reveal additional, currently unrecognized, species.

Read the paper here.

Full Reference:

Evans, D.C., Cullen, T.M., Larson, D.W., and Rego, A. “A new species of troodontid theropod (Dinosauria: Maniraptora) from the Horseshoe Canyon Formation (Maastrichtian) of Alberta, Canada.” Canadian Journal of Earth Sciences Early Online: 813-826. DOI:

Introducing Zuul crurivastator- destroyer of shins, wellspring of science

May 13, 2017

This week, lab postdoc Victoria Arbour and I unveiled a new species of armored dinosaur, Zuul crurivastator, based on an almost complete and remarkably well-preserved skeleton from the Judith River Formation of Montana.  The research describing the new skeleton, identifying Zuul as a new species, and placing it in the family tree of armored dinosaurs was published in the journal Royal Society Open Science ( and is open access.


Artistic life reconstruction of Zuul crurivastator by Danielle Dufault

The new paper was led by Victoria, a globally recognized expert on ankylosaurs, who recently joined the ROM Palaeo team on an NSERC postdoctal fellowship. It was a fantastic experience working with Victoria on the paper – who also deserves big credit for coming up with the awesome name for our new dino. I learned a lot about ankylosaurs from her during this project. We have both really enjoyed working with our amazing palaeo-artist Danielle Dufault, who created the vivid life reconstructions of Zuul for the website, well as the whole behinds-the-scenes Zuul team.  This paper marks the beginning of a larger scientific project on this amazing skeleton and its associated fossils.

The name Zuul is based on similarities between the beautifully preserved skull of our fossil and the terror-dog monster from the 1984 blockbuster film Ghostbusters – both have a broad, rounded snout, gnarly forehead, and two sets of horns behind the eyes. The species name, crurivastator, translates to “Destroyer of Shins”, in reference to its menacing tail, which ends in a massive club-which may have been used to defend itself from predatory dinosaurs or compete with other members of its species.

The research announced today is just the first phase of a larger project focusing on Zuul and its world. The soft tissues are particularly exciting, and we will be conducting research testing for the preservation of biomolecules.  In addition, the 75 million year old river channel deposit that produced Zuul’s skeleton also produced a wide range of well-preserved fossils of other plants and animals living alongside Zuul. These fossils include complete turtles, a crocodile, bones of duck-billed dinosaurs, ostrich dinosaurs, and horned dinosaurs, plus plants, clams, snails and more. We are also conducting research reconstructing Zuul’s palaeoenvironment with geologist Federico Fanti (University of Bologna, Italy), as well as precisely dating the age of the fossil deposit based on volcanic ash deposits with colleagues from the University of Toronto.


The well-preserved and complete tail of the Zuul crurivastator holotype

The rock strata where Zuul was collected are also extensively exposed in southern Alberta, about 50 km to the north, where they are called the Oldman Formation. These rocks have been the focus of a long-term collaborative ROM field project (with Dr. Michael Ryan, CMNH), the Southern Alberta Dinosaur Project, where we have systematically collected thousands of specimens with carefully recorded temporal and environmental context. We can therefore place Zuul and its associated fossils precisely within this framework. In fact, our team is currently digging up a tyrannosaur and a duckbilled dinosaur from the same stream channel complex expressed in Alberta. Within this bigger scientific dataset, Zuul contributes to a much larger understanding of how dinosaur diversity and evolution are related to environmental changes leading up the end-Cretaceous extinction event, which occurred less than 10 million years after Zuul lived.

The Royal Ontario Museum is very excited about Zuul, and there is much more to come, so stay tuned.

Citation: Arbour, V. and D. C. Evans. 2017. A new ankylosaurine dinosaur from the Judith River Formation of Montana, USA, based on an exceptional skeleton with soft tissue preservation. Royal Society Open Science 4: 161086

Zuul Portrait Final

More about Zuul

Read the Open Access paper:

Learn more about Zuul on the ROM website

Read the Press Release

Follow Dr. Victoria Arbour (@VictoriaArbour) and see her blog

Join the Conversation: #DinoZuul @ROMToronto, @ROMPalaeo, @DavidEvans_ROM @VictoriaArbour

Research on Zuul was support by the Natural Sciences and Engineering Research Council of Canada

Teeth of Small, Feathered Dinosaurs Tell a Story of Extinction and Survival

April 21, 2016

Today, my research group published a new paper in the journal Current Biology addressing one of the biggest mysteries of the end Cretaceous mass extinction event- why the did the ancestors of living birds survive, but contemporary small, feathered raptor dinosaurs and primitive toothed birds go extinct?

Our research provocatively suggests that at least some groups of living birds may have their ancestors’ beaks to thank for surviving the asteroid impact and resulting mass extinction that wiped out the dinosaurs.  We show the closest relatives of modern birds, the small feathered raptor dinosaurs and primitive toothed birds, went extinct abruptly at the end of the Cretaceous Period, and that beaked birds may have benefited because of their ability to eat seeds. The study was led by University of Toronto PhD student Derek Larson (now at the Philip J. Currie Museum) and included Dr. Caleb Brown, who graduated a couple of years ago and is now at the Royal Tyrrell Museum– the study took almost five years to complete.


Small, feathered theropod diversity of the Hell Creek Formation, immediately before the asteroid impact. Credit: Danielle Dufault

Several recent studies have suggested that large herbivorous dinosaurs were decreasing in diversity in the last few million years leading up to the end Cretaceous extinction event.  We were interested in seeing if small, feathered dinosaurs and early birds followed this pattern. But their fossil record is extremely fragmentary in the last 20 million years of the Age of Dinosaurs. Therefore, it is difficult to quantify just how many species there were  at any given time and how that changed. The only consistent and informative fossil indicator of their diversity is their teeth- which are abundantly preserved in microfossil bone beds. Interestingly, tooth shape is a key indicator of diet, so we reframed the question from how diverse they were in terms of species, to one that traced the breadth of feeding niches they occupied in the time leading up the extinction event. This would actually provide us with even more information because we could look at the ecology of their extinction.

So we analyzed more than 3,000 of these teeth to give the highest resolution picture of their changing shape and diets over the last 20 million years of the Age of Dinosaurs. The teeth of these bird-like dinosaurs and primitive toothed birds to show that these dinosaurs were a consistent and stable part of the ecosystem leading up to the end of the Cretaceous. There was no evidence of a long term decline- they went extinct very suddenly in geological terms.

Preserved bird and bird-like dinosaur teeth examined in this study were likely suited to eat a variety of animals- insects and small vertebrates.  However, modern birds (Neornithes) are characterized by the shared presence of a toothless beak-so we hypothesized that diet might have been a key factor in their survival. And if the feathered bird-like dinosaurs that ate animals went extinct, perhaps birds survived because they could eat plants, or more specifically, seeds. In the conditions in the wake of the asteroid impact, global forest fires raged and the sun was blocked out by debris ejected into the atmosphere. The ecosystem would quickly lose foliage and animal life. The tooth maniraptoran and early birds were tied to photosynthetic food webs, and my have been more likely to perish.  But seeds would be high-energy packets of food that would persist on the landscape, and any animal that could access them would have an ecological advantage. IF the ancestors of at least some groups of modern birds could access this resource in the critical time period immediately after the impact, that could have been vital.1-fossilteethsThe bird fossil record at the end of the Cretaceous is very incomplete, so the ecologies of species that survived the mass extinction are still largely unknown. With little direct evidence of fossil species surviving the extinction, the reasons as to why some species were able to survive the extinction while their closest relatives went extinct have been unclear.  So we looked to living birds to see if we could test our idea. First, we used the latest family tree of living birds to see if seed-eating was the primitive diet of the early ancestors of living birds.  The data clearly infer that the earliest branches of the bird family tree were likely seed eaters that preferred terrestrial habitats, and were unlikely to be waterbirds- as has been previously suggested. So these groups would have been around when the asteroid hit, and could have benefited from eating seeds during this global crisis. We then looked to present day ecological studies to see what bird flourish in disturbed habitats. Interestingly, it turns out that seed-eating birds are very typically the first vertebrates back into disturbed habitats ravaged by forest fires. This makes sense, because a forest fire will burn all the foliage and decimate the animal population, but seeds can survive in their protective shell, and they can lie dormant for decades, providing food for seed-eating birds.

Its important to keep in mind that extinction patterns at the end of the Cretaceous are complex and involved multiple factors, and we are not proposing that the only reason crown birds survived was seeds. Body size, sensory and metabolic differences, and other factors may have also contributed, and conditions would have affected different bird lineages differently. But small teeth have given us big insights into the extinction patterns of bird-like dinosaurs and primitive birds, and a better understanding of how diet might have played a role in the survival of crown-group bird groups in the wake of the asteroid impact.

Read the paper:

Larson, D.W., C. M. Brown, and D. C. Evans. Dental Disparity and Ecological Stability in Bird-like Dinosaurs prior to the End-Cretaceous Mass Extinction. Current Biology: DOI:

Additional Coverage:

Toronto Star story here.

Globe and Mail Story here.

CSM story here.

CBC story here.

Derek on Quirks & Quarks here.

Introducing Wendiceratops

July 8, 2015

Life reconstruction of Wendiceratops pinhornesis by Danielle Dufault

Life reconstruction of Wendiceratops pinhornesis by Danielle Dufault

Today, Michael Ryan and I published a paper describing a new species of horned dinosaur, Wendiceratops pinhornesis. It is one of the oldest known members of Ceratopsidae, the family of large-bodied horned dinosaurs that includes Triceratops, and it provides new information on the early evolution of skull ornamentation in this iconic group of dinosaurs characterized by their horned faces.


The quarry in southern Alberta where Wendiceratops was excavated.

The bonebed that produced all of the known Wendiceratops fossils is located in southern Alberta, and in rocks of the lowest part of the Oldman Formation that date to approximately 79 million years. The site was discovered in 2010 by Wendy Sloboda, when she was prospecting for new fossil sites as part of our field team. She found numerous bones, including parts of the distinctive frill, coming out of a mud rock layer at the bottom of a very steep hill. In order to uncover more bones, out team had to remove over 20 meters (60 ft) rock above the bonebed layer, which took an entire field season. We started excavation of the site in the summer of 2011, and have collected over 220 bones to date, representing  multiple individuals preserved at different growth stages. The recovered bones represent the majority of the skeleton. This makes Wendiceratops one of the best-known early members of the Ceratopsidae.

Skeletal reconstruction of Wendiceratops pinhornensis by Danielle Dufault.

Skeletal reconstruction of Wendiceratops pinhornensis by Danielle Dufault.

Wendiceratops was about 7 m (20 ft) long, and weighed between 1 and 2 tons when alive- about the size of a hippo. Wendiceratops is distinguished from other horned dinosaurs by an impressive array of gnarly horns curling forward off the back of its neck shield. It also had a prominent, upright horn over the nose, and may have had large brow horns as well, although we have not found this part of the skull.

Wendiceratops means “Wendy’s horned Face”, and it is named after Wendy Sloboda, who discovered the first skull bones of the dinosaur in the remote badlands along the Milk River.  Wendy is legendary for her ability to find fossils in Alberta , where she has discovered literally hundreds of important specimens; more than 2000 specimens are attributed to her in the Royal Tyrell Museum of Palaeontology collections. Given her outstanding contributions to our understanding dinosaurs in Alberta, she deserves a dinosaur.

Mounted skeleton of Wendiceratops on display at the Royal Ontario Museum, Toronto.

Mounted skeleton of Wendiceratops on display at the Royal Ontario Museum, Toronto.

Collecting the bones, preparing them, and mounting them for exhibit was a huge effort, and this was documented in the documentary series Dino Hunt Canada, which celebrates the incredible dinosaur fossil record of the country (find out more at The Wendiceratops project could not have been done without the help of dozens of university students and volunteers helping out with the dig, hundreds of hours of work by skilled technicians in the lab, and our exhibits team- I can’t thank them enough.  A full size skeleton of Wendiceratops and an exhibit documenting its discovery is currently on display at the Royal Ontario Museum in Toronto.


Learn more about Wendiceratops here.

Read the Open Access scientific paper:

David C. Evans and Michael J. Ryan, “Cranial Anatomy of Wendiceratops pinhornensis gen. et sp. nov., A Centrosaurine Ceratopsid from the Oldman Formation (Campanian), Alberta, Canada, and the Evolution of Ceratopsid Nasal Ornamentation.” PLoS One. DOI: 10.1371/journal.pone.0130007

Congrats to Dr. Kirstin Brink!

June 13, 2015

KB_CTKirstin Brink successfully defended her Ph.D. in the Department of Ecology and Evolutionary Biology at the University of Toronto this past Monday. Here thesis is entitled “Phylogenetics and Dental Evolution in Sphenacodontidae (Synapsida)”. Her thesis explores the importance of dental histology for identifying tooth characters for phylogenetic analyses, as well as understanding feeding ecology changes through time in the oldest terrestrial apex predator,  the iconic sail-backed Dimetrodon. ABSTRACT: Paleozoic sphenacodontid synapsids are the oldest known fully terrestrial apex predators, distinguished by strong heterodonty, massive skulls, and well-developed labio-lingually compressed, recurved teeth with mesial and distal cutting edges (carinae). Dimetrodon is an Early Permian (295–272 Ma) sphenacodontid known from southern USA, Canada, and Germany. Dimetrodon is of exceptional importance as it is the most abundant and speciose sphenacodontid, providing valuable information on issues related to the origin of therapsids. Thirteen species of Dimetrodon are currently recognized from hundreds of specimens, but many of these taxa are primarily identified on the basis of size, stratigraphic, and geographic locations. Therefore, little is known about the relationships among species of Dimetrodon or the role they and other sphenacodontids played as apex predators in shaping Early Permian ecosystems. A robust, species-level phylogeny of sphenacodontids will allow for the examination of evolutionary patterns within the clade. The first in-depth description, including histological analyses of several species of Dimetrodon, reveals that the dentition is diverse and bears species-specific morphology. Tooth morphology includes simple carinae with smooth cutting edges and elaborate enamel features, including the first occurrence of cusps and true denticles (ziphodonty) in the fossil record, and the first description of plicidentine in synapsids. The first species-level time calibrated phylogenetic analysis for sphenacodontids, including the enigmatic Bathygnathus borealis, indicates that significant changes within the clade are related to the dental apparatus. This suggests that the morphological changes in sphenacodontids are associated with changes in feeding style and trophic interactions in these ecosystems. The results presented in this thesis are the first steps towards a more comprehensive understanding of evolutionary changes within sphenacodontids and highlights innovations in the group, including the first adaptations towards hypercarnivory.

Congrats to Kirstin on completing her degree. I also want to thank her for her help setting up and running the palaeohistology lab at the ROM.  Kirstin is moving on to a prestigious Killam Postdoctoral Fellowship at the University of British Columbia, working with Dr. Joy Richmond, starting in September.

Evolution of Dinosaur Skin and Feathers: A Complex Story

June 2, 2015

Today, Paul Barrett from the Natural History Museum, Nicolas Campione, a lab alumnus and researcher at Uppsala University, and I published a detailed study of the evolution of dinosaurian integument. Despite extensive recent speculation, our analyses suggest that the majority of non-avian dinosaurs were more likely to have scales than to exhibit ‘feather-like’ structures that are the direct precursors to the feathers we see in modern birds.

Over the past two decades, a number of spectacularly preserved dinosaur fossils with feathers have revolutionized the field of palaeontology. The presence of feathers in birds and their immediate dinosaurian ancestors – theropods like Velociraptor – is uncontroversial, but the presence of true feather homologues, or protofeathers, in other major groups, such as ornithischian dinosaurs, has been highly debated. Several recent discoveries have suggested that, along with scales, filament-like ‘protofeathers’ might have been present in the common ancestor of all dinosaurs and ubiquitous in the entire group.

In order to test the idea that dinosaurs were primitively feathered,  we compiled a comprehensive database of dinosaur skin fossils- the most complete to date- and attempted to reconstruct the evolutionary history of dinosaur scales and feathers using a maximum likelihood approach. Most of our analyses provide no support for the appearance of feathers in the majority of non-avian dinosaurs, and although many meat-eating dinosaurs were feathered, the ancestor of all dinosaurs was probably scaly. Interestingly, the quills and filaments in some major plant-eating ornithischian dinosaur groups were evolutionary experiments that were independent of true feather origins.

Fossilized impression of the scaly skin of the sauropod dinosaur Barosaurus lentus.

Fossilized impression of the scaly skin of the sauropod dinosaur Barosaurus lentus.

Untangling when particular integumentary features first evolved will help us understand the origins of feathers and why they first arose, but our analyses are limited to the data we have at hand and questions still remain. Importantly, our research also quantifies taphonomic biases and identifies gaps in the fossil record of dinosaur skin. The biggest and most significant gap is in the Triassic and Early Jurassic, when dinosaurs first originated and diversified, where very few integument fossils are known. Rocks of this age also lack significant lake/lagoonal fossil sites where delicate feather-like structures are preferentially preserved. This makes the origin of the direct filamentous precursors to feathers difficult to pinpoint. Whether or not the first dinosaurs had true ‘protofeathers’ may only be finally resolved with the discovery of more fossils, particularly from early in dinosaur evolutionary history.


P. M. Barrett, D. C. Evans, and N. E. Campione. 2015.  Evolution of dinosaur epidermal structures. Biology Letters. 20150229. Doi:

Press Release:

Origins of feathered dinosaurs more complex than first thought


Feathers or scales? New research highlights dinosaur diversity

Most dinosaurs had scales, not feathers, fossil analysis concludes